======= Date Modified 23 Dec 2008 23:31:30 =======
Your questions are really specific procedural things, so I can't see how anyone would know the answers unless they know you, your uni and your funding situation. You need to find out where the responsibility lies for the financial issues you're asking about, and then you'll know who signs off what and how. You should have a finance officer you can ask.
It might be worth checking the details of any funding awards/studentships if you've got one, to see if the awardee has to submit an end of project or interim project monitoring report. Sometimes, though maybe for larger research projects rather than PhDs, a requirement of getting funding is to write a report at the end, which may include details of how the money was spent. It wouldn't be an odd requirement for any funding body to want to know how their money's been spent, particularly if it's public money, as I would expect there to be some form of financial accountability needed at some stage.
All students at my uni all have an individual budget allocation that can be spent on travel, conferences, specialist software etc. The student has to justify why that expenditure is necessary for their research and why the money should be spent accordingly, plus has to keep evidence of the expenditure for the eventual finance audits as invoices, receipts etc. All this has to be agreed with their supervisors before the money is spent.
I've no idea whether any of this is relevant to your particular case though.